The microencapsulation of calcium chloride hexahydrate as a phase‐change material by using the hybrid coupler of organoalkoxysilanes

Abstract

A novel method of microencapsulation for inorganic salt hydrates as phase‐change material (PCM), which is essential for their broad application, was pursued by combining sol–gel process with interfacial polymerization. Calcium chloride hexahydrate (CCH), chosen as a representative PCM of salt hydrates, was used as a core material, and organoalkoxysilane was applied to provide hybrid properties of mediating the hydrophilic core and hydrophobic shell material. The Fourier transform infrared spectra and SEM images confirmed that the siloxane and polyurea shell material successfully capsulated the CCH core. Fine morphology of microcapsules was further investigated with SEM, and it presented almost‐spherical shape and a well‐defined core–shell structure. Thermogravimetric analysis indicated that microcapsules containing CCH have sufficient thermal stability, which usually degraded in four steps. Differential scanning calorimeter investigation confirmed additionally that the microencapsulated CCH absorbs thermal energy with phase change during the melt process but undergo a severe super cooling phenomenon in the crystallizing process. In addition, the durability test was conducted to evaluate the siloxane polymer and polyurea as a shell material, protecting CCH from leaking. The effect of pH and the ratio of ingredients were studied in terms of encapsulation possibility and performance of core PCM, which include morphology of core–shell particles and essential thermal properties as a PCM. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45821.

Novel Hybrid Hypercrosslinked Polymer Assisted Highly Efficient Thermal Energy Storage

“…Shape-stabilization strategy provides a feasible venue for the practical utilization of inorganic PCMs. 57,58,59 For example, Yang et al 60 obtained hybrid properties by combining sol-gel method with interfacial polymerization, taking calcium hexahydrate (CCH) as the representative polychlorinated biphenyl (PCMs) of salt hydrate as the core material, and using organic alkoxysilane as the medium of hydrophilic core material and hydrophobic shell material. The Fourier transform infrared spectra and SEM images con rmed that siloxane and polyurea shells successfully encapsulated the CCH core layer.…”

Review of Encapsulated Salt Hydrate Core-Shell Phase Change Materials

“…, and so on (Sharma S.D. et al, 2004;Sharma A. et al, 2009;Cabeza L.F. et al, 2011;Su W. et al, 2015;Yang J.M. and Kim J.S., 2017).…”

Distribution of microencapsulated phase change material on a plate, and inhibited build‐up of temperature in response to a constant heat flux

“…The other considerations are small volume changes on phase transformation, high rate of crystal growth, chemical stability, completely reversible melt and freeze cycle and more importantly, the least degradation after a large number of melting‐freezing cycles. These properties are found favourably in a few hydrocarbon materials (such as n ‐octane, n ‐decane, n ‐dodecane and paraffin), salt hydrates and in some eutectic mixtures 1‐4 . However, the organic PCMs are flammable, whereas the salt hydrates are corrosive in nature, requiring a novel procedure to attach to the heat producing surfaces.…”

“…There has been a recent interest in leveraging the near‐ambient melting point, reasonably high latent heat of fusion, and low cost of production of this PCM 29 . The method of microencapsulation for this PCM has also been addressed in recent literature reports 4 . Other than distributing the microcapsules over the surface of the plate, an alternative arrangement is also considered by placing the entire PCM in a container at the centre of the plate.…”